1. Field of the Invention
The present invention relates to an image forming apparatus for performing at least a copying function that scans an image of an original document and forms an image on a transfer sheet based on scanned image data, and more particularly relates to a multi-functional digital image forming apparatus in which at least one application function is added to the copying function.
2. Discussion of the Background
With regard to a background multi-functional digital image forming apparatus that performs copying, faxing, printing, and scanning functions, an image processing device in which a memory is effectively used in multiple functions, a control mechanism including an expansion unit is shared, and resources for each image processing device are effectively utilized has been proposed. Such a multi-functional digital image forming apparatus includes a construction that allows resources for each image processing device to be shared while controlling a plurality of application programs.
FIG. 1 is a block diagram of an entire configuration of a background image processing device. An image reading unit 1301 optically reading an image of an original document includes a lamp, mirrors, and a lens. Reflected light of the lamp irradiation by the original document is collected onto a photoreceptor through the mirrors and the lens.
The photoreceptor, for example, a CCD (Charge Coupled Device) is installed on a sensor board unit 1302. The image data converted into an electrical signal by the CCD is converted into a digital signal for output from the sensor board unit 1302.
The image data, which is output from the sensor board unit 1302, is input to an image data control unit 1303. The image data control unit 1303 controls all the transmission of the image data between functional devices and a data bus. The image data control unit 1303 performs data transfer of the image data among the sensor board unit 1302, a parallel bus 1320, and an image processing processor 1304, and performs communication between a system controller 1331 for the entire control of the image processing device and a process controller 1311.
The image data output from the sensor board unit 1302 is transferred to the image processing processor 1304 through the image data control unit 1303, and is output to the image data control unit 1303 again, after correction of signal degradation (signal degradation of the scanner system) due to the optical system and quantization into digital signals.
There are two kinds of jobs, that is, a job to re-use the read image data after storage in a memory, and a job not to reuse the read image data without storage. Hereinafter, the two jobs will be described. As an example of a case of storing the image data in the memory, when a plurality of copies are made for one sheet of an original document, the image reading unit 1301 is operated one time to read an image of the original document, and read image data is stored in the memory. The read image data in the memory is read out a plurality of times for making a plurality of copies. As an example of a case of not storing the image data in the memory, when one copy is made for one sheet of an original document, the read image data is reproduced as it is. Therefore, the access to the memory is not necessary.
In the case of not storing the image data in the memory, the image data transferred from the image processing processor 1304 to the image data control unit 1303 is returned again to the image processing processor 1304 from the image data control unit 1303. The image processing processor 1304 performs image quality control of conversion of the brightness data obtained by CCD into the area gradation.
The image data after the image quality processing is transferred to a video data control unit 1305 from the image processing processor 1304. After post-processing of signals, which are changed into area gradation data, for dot arrangement, and pulse control for reproducing the dots, a reproduced image is formed on a transfer sheet in an image forming unit 1306.
Hereinafter, a description will be made of flow of image data during additional processing, such as, for example, rotation of the image direction and image synthesis, which is performed when retrieving image data stored in the memory. The image data transferred from the image processing processor 1304 to the image data control unit 1303 is sent to an image memory access control unit 1321 from the image data control unit 1303 via the parallel bus 1320. In the image memory access control unit 1321, access control of image data and a memory module 1322, expansion of print data of an external personal computer (PC) 1323, and compression/expansion of image data for effective use of the memory are performed based on the control of the system controller 1331.
The image data sent to the image memory access control unit 1321 is stored in the memory module 1322 after data compression to read out the stored image data as required. The read-out image data is expanded, restored to original image data, and returned to the image data control unit 1303 from the image memory access control unit 1321 via the parallel bus 1320.
After transferring to the image processing processor 1304 from the image data control unit 1303, image quality processing, and pulse control in the video data control unit 1305 are performed, and a reproduced image is formed on a transfer sheet in the image forming unit 1306.
The multiple functions of the digital image forming apparatus are achieved by bus control at the parallel bus 1320 and the image data control unit 1303 in the image data flow. The facsimile transmission function performs image processing of the read image data in the image processing processor 1304, and transfers the data to a facsimile control unit 1324 via the image data control unit 1303 and the parallel bus 1320. Data conversion of the data for the communication network is performed in the facsimile control unit 1324, and the data is sent to a public network 1325 as facsimile data.
As for the received facsimile data, line data from the public network 1325 is converted into image data in the facsimile control unit 1324, and transferred to the image processing processor 1304 via the parallel bus 1320 and the image data control unit 1303. In this case, special image quality processing is not performed, and reproduced images are formed on a transfer sheet in the image forming unit 1306 after dot re-arrangement and pulse control in the video data control unit 1305.
When a plurality of jobs, for example, copying function, facsimile sending and receiving function, and printer output function are simultaneously operated, a system controller 1331 and the process controller 1311 control job allocation of the right of using the image reading unit 1301, the image forming unit 1306, and the parallel bus 1320. The process controller 1311 controls the flow of image data, and the system controller 1331 controls the entire system and manages the activation of each resource.
As for function selection of the multi-functional digital image forming apparatus, processing contents, such as the copying function, and the facsimile function, are set by selection input on an operation panel 1334. The system controller 1331 and the process controller 1311 communicate each other though the parallel bus 1320, the image data control unit 1303, and the serial bus 1310. Specifically, in the image data control unit 1303, communications between the system controller 1331 and the process controller 1311 are performed by converting data formats to each other for respective data interfaces to the parallel bus 1320 and the serial bus 1310.
Input/output signals to/from a drive mechanism and various kinds of sensors in an image forming apparatus are detected and controlled at the port of an I/O control unit 1340. The process controller 1311 controls the signal detection and drive signals, and monitors output signals from the sensors.
The above-described background image processing device has a configuration in which resources are shared by multiple application functions. In this case, for a user who requests to use only a basic function (i.e., a copying function), unnecessary constructions are included in the above image processing device, thereby causing the increase of the cost of an apparatus and undesired power consumption.